ScienceShot

ScienceShot: Hitchhikers From the Deep

Are deep-sea submersibles bringing back creatures from the ocean depths? Scientists have long discounted the notion, arguing that the immense pressure differences would kill any hangers-on. But a new report suggests that some organisms retrieved from sea-floor vent systems may survive long enough at the surface to be transported to another undersea oasis. In September 2004, researchers used the deep-sea submersible Alvin to collect samples from the sea floor at a site more than 2200 meters deep off the coast of Washington. Besides retrieving a couple of wooden objects left there 2 years earlier, the researchers slurped up some of the underlying sediments to collect the creatures living there. But some of the creatures—especially limpets (shown), a type of marine snail—seemed out of place at the site, which wasn't an active hydrothermal vent. Turns out, the creatures had hitched a ride on Alvin from a hydrothermal vent about 635 kilometers away, a site they'd visited just 2 days earlier. Evidence that the limpets were stowaways, reported online today in Conservation Biology, includes the ratios of carbon and nitrogen in the creatures' tissues and shells, as well as the ratio of males and females in the sample—a characteristic that varies from one hydrothermal site to another. The new findings point out the risk of transferring organisms, along with their parasites and diseases, from one vent site to another. Scientists could help prevent stowaways by drying their equipment between deployments, the researchers say, or by rinsing their equipment with fresh water or a peroxide solution.